Smart Process Distillation Application Improves Recovery And Saves Energy


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Presented by Pete Sharpe at Emerson Exchange 2009.

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  • Main Points: DeltaV PredictPro has a powerful built-in optimizer which will push the process to the most profitable operation, within constraints. Often optimization can be as simple as maximizing one variable to the most limiting constraint. For example, huge benefits can be realized by maximizing throughput to an equipment constraint. Whereas the operator may only make moves occasionally, APC can make moves continuously, 24 hours a day. However, for complex processes, the optimization involves many variables and requires a more powerful tool, like DeltaV PredictPro.
  • 14 Amp reduction due to lower discharge pressure, 329 days/year 49 Amp additional reduction due to lower minimum flow, 122 days/year [14A*0.9year + 49A*0.33year]*4160V*sqrt(3)* 0.95W/ VA * 1KW/1000W*24hr/day*364day/year *$0.05/KWH = $86,000/yr
  • Smart Process Distillation Application Improves Recovery And Saves Energy

    1. 1. SmartProcess Distillation Application Improves Recovery and Saves Energy – A Case Study Pete Sharpe Director, Industry Solutions for Refining & Chemicals
    2. 2. Presenters <ul><li>Pete Sharpe </li></ul>
    3. 3. Agenda <ul><li>Operating Challenges </li></ul><ul><li>Project Methodology </li></ul><ul><li>Process Overview </li></ul><ul><ul><li>Process Flow </li></ul></ul><ul><ul><li>Operating Objectives </li></ul></ul><ul><li>SmartProcess® Distillation Optimizer </li></ul><ul><li>Results </li></ul>
    4. 4. Operating Challenges <ul><li>Purification unit involving multiple distillation trains with 11 columns </li></ul><ul><li>Ultra-high purity product specifications require very tight quality controls </li></ul><ul><li>Multiple large, 200+ tray columns with extremely long time constants </li></ul><ul><li>Large energy consumer </li></ul><ul><li>Different feedstock suppliers with different qualities unloaded from railcars </li></ul><ul><li>Safety margins required to compensate for disturbances in feed quality </li></ul>
    5. 5. Project Methodology <ul><li>APC licenses were specified and included as part of the DeltaV migration project </li></ul><ul><ul><li>Capital expense </li></ul></ul><ul><li>Functional Specification prepared by Emerson that included the design for the complete process unit (11 distillation columns) </li></ul><ul><li>Initial implementation phase covered only the first column in the series </li></ul><ul><ul><li>Gain customer experience with technology </li></ul></ul><ul><ul><li>Develop Operator acceptance </li></ul></ul><ul><ul><li>Demonstrate value to management </li></ul></ul><ul><li>Subsequent phases to be implemented by customer engineers with support from Emerson APC Consultants </li></ul>
    6. 6. Project Implementation <ul><li>FDS phase included on-site audit of instrumentation and control strategies and preliminary step tests </li></ul><ul><ul><li>Identified regulatory control issues that needed to be addressed prior to on-site work </li></ul></ul><ul><li>Software installation of SmartProcess application performed by customer personnel prior to on-site work </li></ul><ul><li>Emerson consultants spent 2 weeks on-site for configuration and commissioning </li></ul><ul><li>Performance improvements estimated and presented to operations management based on initial trial run </li></ul>
    7. 7. Advanced Control Solution <ul><li>SmartProcess® Distillation Optimizer </li></ul><ul><ul><li>Utilizes Embedded DeltaV Advanced Process Control </li></ul></ul><ul><ul><li>On-Line Key Performance Indicator (KPI) Calculations </li></ul></ul><ul><li>Emerson APC Consulting Services </li></ul><ul><ul><li>Functional Design </li></ul></ul><ul><ul><li>Control Performance Audit </li></ul></ul><ul><ul><li>Implementation Assistance </li></ul></ul><ul><li>Initially started with first column in the train that removes light contaminates </li></ul>
    8. 8. Process Overview Bottoms Main Product Feed 1 <ul><li>Column separates components based on different boiling points </li></ul><ul><li>Tray temperatures reflect composition on that tray, but need to be compensated for pressure </li></ul><ul><li>Control strategies based on “What comes in must go out” </li></ul><ul><ul><li>Material Balance </li></ul></ul><ul><ul><li>Energy Balance </li></ul></ul><ul><li>Material Balance: </li></ul><ul><ul><li>OH / Feed Ratio </li></ul></ul><ul><li>Energy Balance: </li></ul><ul><ul><li>Reflux / Feed Ratio </li></ul></ul>Feed 2 At constant OH rate, this temp sets the energy balance (R/F). Internal Reflux Lt Ends Impurities This flow sets the material balance (D/F) Complicated OH condenser system LC TC TI
    9. 9. Distillation Process Affect of Energy Lt Key Concentration Energy Consumption  Feed Composition 100% 0% Overhead Composition Bottoms Composition At Constant D/F Ratio
    10. 10. Cost of Variability Precision Control Valves Loop Performance Digital Positioners Better Measurements IMPROVED PROFIT BY CHANGING TARGET REDUCED VARIABILITY POOR CONTROL $ PROFIT SPECIFICATION LIMIT Improvements from: Operator Safety Margin Advanced Control
    11. 11. APC Optimization Time Distillate Rate Recovery Opportunity Minimum OH Rate Operator Setpoint APC Objective: Minimize overhead product loss while controlling bottoms impurities to target
    12. 12. SmartProcess Applications – Tools vs. Solutions We have the best materials, craft skills, tools, and services. What can we build for you? We’ve developed a variety of houses to meet your specific needs. Products, Services, Expertise Applications
    13. 13. What are SmartProcess Applications? <ul><li>Re-usable applications that can be pre-engineered and used multiple times </li></ul><ul><li>Combination of: </li></ul><ul><ul><li>DeltaV composite blocks, modules & templates </li></ul></ul><ul><ul><li>APC tools (e.g. PredictPro, Neural) </li></ul></ul><ul><ul><li>DeltaV Graphics </li></ul></ul><ul><ul><li>Documentation </li></ul></ul><ul><ul><li>Sample Configuration </li></ul></ul><ul><ul><li>Simple dynamic simulation </li></ul></ul>
    14. 14. Applications Enable Faster, More Efficient APC Implementations Functional Design Det. Design, Config & Staging Step Tests & Model ID Commissioning Functional Design Det. Design & Config Step Tests & Model ID Commissioning Commissioning Step Tests & Model ID F.D. & Config Traditional APC Technology Embedded APC Technology SmartProcess ® Applications with Embedded APC
    15. 15. SmartProcess Distillation Control Module Standard Distillation Calcs Predict Block Preconfigured Neural Blocks Module Library
    16. 16. Standard Operator Display & Simulation
    17. 17. <ul><li>Manipulated Variables (MV) – Controller setpoints written to by the MPC. </li></ul><ul><ul><li>Distillate Rate </li></ul></ul><ul><ul><li>Reboiler Steam </li></ul></ul><ul><li>Controlled Variables (CV) - Process variables which are to be maintained at a specific value; i.e., the setpoint </li></ul><ul><ul><li>Lower tray Pressure Compensated Temperature (PCT) </li></ul></ul><ul><ul><li>Overhead PCT </li></ul></ul><ul><li>Disturbance Variables (DV) - Measured variables which may also affect the value of controlled variables </li></ul><ul><ul><li>Feed Flows (2) </li></ul></ul><ul><ul><li>Reflux Temp </li></ul></ul><ul><li>Constraints (LV) - Variables which must be maintained within an operating range (a special type of CV) </li></ul><ul><ul><li>Overhead product loss (on-line analyzer) </li></ul></ul><ul><ul><li>Light impurities in bottoms (on-line analyzer) </li></ul></ul><ul><ul><li>Internal Reflux Rate </li></ul></ul><ul><ul><li>Column Delta Pressure </li></ul></ul><ul><ul><li>Reflux/Distillate Ratio </li></ul></ul>Key Process Variables
    18. 18. Process Issues <ul><li>Reboiler steam instability </li></ul><ul><ul><li>Interaction between parallel reboilers with common steam trap, one fouled, one clean. In Manual and Auto, steam flow varied ~10kLb/Hr out of 50. Process design issue. </li></ul></ul><ul><ul><li>Caused ~0.5 Deg F variability in tray temp used as CV </li></ul></ul><ul><li>Overhead pressure controller range </li></ul><ul><ul><li>Pressure is controlled by two valves in the condenser system, one large and one small </li></ul></ul><ul><ul><li>OH PIC operates small valve with large valve normally in Manual. </li></ul></ul><ul><ul><li>Small valve had insufficient range to control between day and night </li></ul></ul><ul><ul><li>Pressure swings caused changes in temps and qualities </li></ul></ul><ul><ul><li>Implemented control function to adjust large valve to keep small valve in control range </li></ul></ul><ul><li>Small process gains </li></ul><ul><ul><li>Issue primarily due to big difference in instrument ranges </li></ul></ul><ul><ul><li>Solved by using scaler blocks for process inputs </li></ul></ul>
    19. 19. Reboiler Flow Variability Steam Condensate Drum Parallel Reboilers Tray Temps Spare Fouled Clean FC TC LC
    20. 20. Pressure Effects OH and Btms compositions show day-night swing due to column pressure Pressure looked fairly stable
    21. 21. Steam Step Tests Test Compromised due to OH pressure swings Btms Impurity OH Prod Loss Rebolier Out T OH Pressure Steam
    22. 22. Model Verification Btm PCT Btm Impurity OH Composition Top PCT
    23. 23. Initial Closed Loop Operation – Small Gains Both MV’s slowly reduced, but no observable control action
    24. 24. Initial Controller Results OH Prod Loss Btm Impurity OH PCT Btm PCT Steam OH Flow Step Tests APC ON
    25. 25. Summary of Results <ul><li>Controller immediately started reducing distillate rate and OH product losses </li></ul><ul><li>Average OH product loss reduced by approximately 22% </li></ul><ul><li>Impurities in Btms were maintained within specifications. </li></ul><ul><li>Steam usage reduced on average around 7% </li></ul><ul><li>Estimated value over $700k per year </li></ul>
    26. 26. Summary <ul><li>High-purity distillation columns offer significant opportunities for improvement from APC </li></ul><ul><li>A SmartProcess® Distillation Optimizer was implemented on a large purification column </li></ul><ul><li>Following the functional design, the project was completed in 2 weeks on-site </li></ul><ul><li>Excellent project payback achieved </li></ul>
    27. 27. Where To Get More Information <ul><li>Exhibit Hall </li></ul><ul><ul><li>SmartProcess Booth </li></ul></ul><ul><ul><li>Emerson Consulting Booth </li></ul></ul><ul><ul><li>DeltaV Advanced Control Booth </li></ul></ul><ul><li>Contacts: </li></ul><ul><ul><li>[email_address] </li></ul></ul><ul><li>Website: </li></ul><ul><ul><li> </li></ul></ul>